Genetic Identity, Diversity, and Population Structure of CIP's Sweetpotato (I. batatas) Germplasm Collection.

Noelle L Anglin,Norma Manrique,Rocio Alagon,David Ellis,Genoveva Rossel,Ana Panta,Ronald Robles,Robert L Jarret

doi:10.3389/fpls.2021.660012

Abstract

The in trust sweetpotato collection housed by the International Center of Potato (CIP) is one of the largest assemblages of plant material representing the genetic resources of this important staple crop. The collection currently contains almost 6,000 accessions of Ipomoea batatas (cultivated sweetpotato) and over 1,000 accessions of sweetpotato crop wild relatives (CWRs). In this study, the entire cultivated collection (5,979 accessions) was genotyped with a panel of 20 simple sequence repeat (SSR) markers to assess genetic identity, diversity, and population structure. Genotyping and phenotyping of in vitro plantlets and mother plants were conducted simultaneously on 2,711 accessions (45% of the total collection) to identify and correct possible genetic identity errors which could have occurred at any time over the thirty plus years of maintenance in the in vitro collection. Within this group, 533 accessions (19.6%) had errors in identity. Field evaluations of morphological descriptors were carried out to confirm the marker data. A phylogenetic tree was constructed to reveal the intraspecific relationships in the population which uncovered high levels of redundancy in material from Peru and Latin America. These genotypic data were supported by morphological data. Population structure analysis demonstrated support for four ancestral populations with many of the accessions having lower levels of gene flow from the other populations. This was especially true of germplasm derived from Peru, Ecuador, and Africa. The set of 20 SSR markers was subsequently utilized to examine a subset of 189 accessions from the USDA sweetpotato germplasm collection and to identify and reconcile potential errors in the identification of clones shared between these collections. Marker analysis demonstrated that the USDA subset of material had 65 unique accessions that were not found in the larger CIP collection. As far as the authors are aware, this is the first report of genotyping an entire sweetpotato germplasm collection in its entirety.

Highlights

Sweetpotato is an important crop globally as a versatile food source in that both the roots and the leaves can be consumed
Accessions from Africa, Asia, and the Pacific were mostly transferred via a donation from the following collections: the International Institute of Tropical Agriculture (IITA) in Nigeria, the Asian Vegetable Research Center (AVRDC) in Taiwan ( The World Vegetable Center), and the CIP regional office in Kenya
Wadl et al (2018) evaluated part of the USDA sweetpotato germplasm collection of 417 accessions and reported peaks occurring at K = 2 and K = 4, similar to the results reported in Supplementary Figure 4

Summary

Introduction

Sweetpotato is an important crop globally as a versatile food source in that both the roots and the leaves can be consumed. Sweetpotato is widely cultivated in many developing countries where the yields are well below the average, compared with developed countries. Sweetpotato is an important source of income for women compared with men in developing countries, such as Nigeria, due to its low input requirements and short maturity time relative to other crops (David, 2015). Sweetpotato grows well on marginal soils with limited inputs and is tolerant to a wide range of climatic conditions making production improvements feasible (Lebot, 2008). Sweetpotato is a versatile food source that is nutritionally beneficial for human health and serves a medicinal role in many parts of the world. Roots contain simple and complex carbohydrates, vitamins (A, B1, B5, B6, and C), minerals (iron, calcium, magnesium, manganese, and potassium), fiber, flavonoids, phenolics, and iron, while the leaves contain protein, fat, fiber, ash, carbohydrates, vitamins (A and C), minerals, and low levels of toxicants (phytic acid, cyanide, tannins, and oxalate) (Mohanraj and Sivasankar, 2014)

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